Organ percussion system providing percussive harmonic synthesis



Nov. 25, i969 NI R KOHLS ET AL 3,480,7l8

SYSTEM PROVIDING PERCUSSIVE HARMONIC SYNTHESIS ORGAN PERCUSSION Filed June 23, 1966 5 Sheets-Sheet l Nov. 25, '1969 NA R. Kor-n.5 ETAL 3,480,718

ORGAN FERCUSSION SYSTEM PROVIDING PERCUSSIVE HARMONIC SYNTHESIS Filed June 25, 1966 3 Sheets-Sheet z gm; 1 1 s l l 5 55 152 Nov. 25, 1969 ORGAN PERCUSSION SYSTEM PROVIDING PERCUSSTVE I-IARMONIC SYNTHESIS` Filed June 23, 1966 N. R. KOHLS ETAI- 3 Sheets-Sheet (-3 12'? 20 JJZ- f4 Z JQa/fd 6 4.0 Q02 pgecass/o/v ,12v/awa iff BAM/Jo jf? PEIM? P/QEI/w PRE/WWP Zf ff@ I-E LA l/,' LVI: L,\250 u I Z 0 553:@ I II L 5 I I ffii; 232

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j/ye/fa/": 72m 75M@ wg/)we f7. 72 Z9 W MOMZM g/M t United States Patent O 3,480,718 ORGAN PERCUSSIDN SYSTEM PROVIDING PERCUSSIVE HARMNIC SYNTHESIS Norman R. Kohls, Morton Grove, Clarence A. Nykl, Jr., Park Forrest, and William R. Ayres, Park Ridge, Ill., assignors to Hammond Corporation, Chicago, Ill., a

corporation of Delaware Filed `lune 23, 1966, Ser. No. 559,829 Int. Cl. G10h 1/02 U.S. Cl. Slt-1.01 13 Claims ABSTRACT 0F THE DISCLOSURE An electronic organ which provides both sine wave and bright wave sources and includes a percussive system which utilizes selected constituents of each of the sources either in additive synthesis or by formanting as desired. Synthesis is accomplished by joint voice tab and playing key control of junctions in a transistor matrix, such that output from the matrix depends upon both tab and key actuation of connections leading to individual matrix junctions, the playing keys controlling the frequency of the note sounded and the voice tabs the harmonic content thereof.

This invention relates to an organ percussion system, and more particularly to a percussion system which combines the synthesis approach, which adds selected harmonics to the output as required, with the formant, bright wave system so as to give an appropriate optional response as required by the organist.

It is therefore a principal object of this invention to provide an improved percussion system which combines features of a synthesis type organ and a formant organ.

Another object is to provide a novel system of the above described character which will provide percussive tones having a complex harmonic structure, depending upon what is suitable for the purpose, and which harmonies are selected in a simple fashion by the organist.

Yet another object is to accomplish the above and additional desirable organ percussive features at reasonable cost.

Other objects and advantages will become apparent from the following description of the invention taken in conjunction with the accompanying drawings in which:

FIG. 1 is a diagrammatic box representation of a system which embodies the present invention; and

FIG. 2 is a more detailed representation of the major portion of the system.

In the synthesis approach to organ design, a multiplicity of sine wave or flute signals is made available, one for each fundamental frequency within the compass of the instrument, plus other frequencies which lill in harmonies not occurring as fundamentals. yOrdinarly these various frequencies are mixed as required to give the selected response. A basic scheme for accomplishing this forms the subject of Hammond Patent No. 1,956,350. Another approach which uses proportional keying of a convenient basic waveform is explained in Schrecongost and Ring patent application Ser. No. 491,974. These systems provide organ sustained tones, however, and do not lend themselves Well to the provision of percussive effects, particularly if the percussive tones are to include a reasonable collection of harmonics. This is at least partially because a large group of contacts for each play- 3,480,718 Patented Nov. 25, 1969 ICC ing key must be provided to take care of the organs requirements for sustained tones, and if another considerable group of contacts is added to this collection to pro- -vide for percussive tones, the number of contacts becomes excessive. For some purposes, however, synthesized percussive tones best provide the desired effect. On the other hand, there are certain percussive effects which are best achived .by starting with bright wave signals containing a full harmonic series, and such a system is not easily combined into a system which will give synthesized percussive tonal effects.

In addition to the above generalizations, it should be understood that percussive keyers are available, such that the playing of a key has the effect of supplying a tone signal called for to the organ output system With a percussive envelope. For example, see Milho Patent No. 3,247,306, or Schrecongost patent application Ser. No. 458,257, or Kohls patent application Ser. No. 544,066.

For the purpose of this exposition, it will be assumed that organ tone generator structure is available to provide all desired tone signals in the form of bright waves and that, to provide a complete instrument, there will be auxiliary means for providing sustained organ tones in addition to the percussive system which forms the subject of this invention. Both the customary sustained tone system and the present percussion system may, of course, use the same basic tone generators, or optionally, they may separate.

In the interest 0f convenience, the various tone signals will be referred to hereinafter, and in the drawings, by number, such as frequency 37, frequency 53, and so on. Those not familiar with this common method of frequency designation are referred to the previously mentioned Hammon patent which explains the system and provides a `chart which correlates frequency numbers with frequencies in cycles per second.

Referring to FIG. 1, a generator of bright Wave signals is shown at 10. So far as this invention is concerned, the generator system may be of any type which supplies bright Waves; that is, tone signals which have present a full series of both even and odd harmonics. Such signals commonly are of sawtooth waveform. Of course, for other purposes, the generator system may also supply square wave signals Without appreciable even harmonies, or even sine waves, which may be variable in the musical instrument organization; the frequencies supplied may be less or exceed the range of tone signals from 13 to 96 which are indicated. In the interest of being specific, however, this disclosure will be based upon the assumption of a source of bright wave signals from 13, which is C at about 65.4 Hz., to 96, which is B at about 7902 Hz.

Each of the signal leads from the generator 10 is connected through its individual percusion keyer at 12 and thek outputs from the keyers are collected in groups and passed to filter drivers at 14. The percussion keyers are under the control of the individual playing keys and certain accessories at 16, so far as selection of the note to be sounded is concerned. A harmonic selector system, a portion of which is at 18, is used to choose the finally synthesized harmonic content of the tone signals fed to the output. Control over the percussion keyers is also exercised so as to give short, medium, or long decay to the percussive envelope. Contacts which are a portion of the harmonic selector are actuated by the tab controls at 20, and supply the information to the harmonic selector portion at 18 to determine the choice of harmonics. Other tab actuated contacts control keyers 12 to determine the choice of a short, medium, or long decay envelope. In addition to the above, the tab controls 20 also perform other control functions as will appear presently.

The filter drivers 14 are amplifiers and boost the signals prior to filtration. Filtration is accomplished, with the exception of the low frequency group 13 to 24, by the joint treatment of half octave segments. These half:` octave segments are: to 30, 3l to 36, 37 to 42, 43 to 48, 49 to 54, 55 to 60, 61 to 66, 67 to 72, 73 to 78, 79 to 84, 85 to 90, and 91 to 96. Since the bright wave signals contain both even and odd harmonics, and since the closest harmonic to the fundamental is the second at twice the frequency, it will be seen that single filters can be used to strip all bright wave signals over a half octave range of all harmonic structure and pass only the fundamental sine waves.

The group of signals 13 to 24 covers a full octave, and complete filtration to leave only sine waves is not necessary with this group, since at these low frequencies the lack of discrimination of the listener makes such full treatment of the signals unnecessary. If desired, this group could be split and passed through separate filters.

To avoid crowding the drawings, only three of these filters are shown connected to the output leads 24 from the drivers at 14. They are for signal groups 13 to 24, 73 to 78, and 79 to 84. The other leads 24 are shown, however, and it will be understood that each of these is connected to its own filter 22.

Whatever signals get through the filters 22 are collected in the sine wave lead 26 and passed through apercussion preamplifier 28 and thence to the output terminal 30 by way of the tab control system 20. The output terminal 30 will be connected through whatever is desired, such as reverberation or vibrato systems or the like, and swell control mechanism and power amplifiers, eventually to one or more speakers, all of which may be conventional and to some extent a matter of choice and, in any event, not a part of the present invention; therefore, no description is necessary here.

The leads 2-4 from the filter drivers 14 are also connected to individual piano and banjo formants 32. These formant corcuits do not act to remove all harmonics of the fundamental as do the filters 22, but, in the usual formant fashion, remove or attenuate certain frequencies and enhance or peak certain others, so as to give the type of tone coloration desired by the particular designer. It is not the purpose of this explanation to dictate what formants should be used for this purpose, although a suitable example will be given presently. Rather, what is important is that the percussion system of this invention provides both for the obtaining of percussion effects by formanting of bright waves and by the synthesis of sine waves, together with appropriate control of the percussion envelope in both cases.

The piano tones, taken from the formant 32 by way of lead 34, pass through a piano preamplifier 36 to the output terminal 30` under control of the tab system at 20. Similarly, the banjo signal is taken through lead 38 and banjo preamplifier 40 to the output by way of the cab control system 20'.

The piano and banjo tones, taken from the formants 32 through separate leads 34 and 38, respectively, pass through respective preamplifiers 36 and 40, and thence to the tab control system 20 on their way to the output terminal 30.

Note that the frequency groups 79 to 84, 85 to 90, and 91 to 96 have no piano and banjo formant connections, since note No. 73 is the uppermost fundamental tone at so-called 8-ft. pitch. The higher frequency signals are used for the synthesis of certain percussive tones requiring upper harmonic structure.

As will be explained presently, the box 16 labeled keyboard and accessories includes, among the accessories, an arrangement for reiteratng the percussion envelope, and also a mechanism which facilitates the playing of arpeggios. It will be appreciated that these particular effects and the particular percussive stops used in the more detailed explanation to follow are not intended to be limitative; rather, they are for the purpose of illustrating how the system of this invention frees the designer to obtain a wider variety of musically useful percussive effects than have been available heretofore.

In FIG. 2, the generator 10 for signal 13-which is the frequency to be used, for example only, in most of this description-supplies its percussion keyer 12 by way of lead 50. In the keyer, lead S0' is connected through capacitor 52 to the emitter of transistor 54, the emitter also being connected to ground by way of resistor 56. The collector is connected to the output at 58 to which also are connected the outputs of the other keyers in the signal group 13 to 24, and this lead is also connected through a resistor 59 to a source of potential at +15 v. The base circuit of the transistor 54 is arranged to controlthe conduction cycle, or in other words, the percussive envelope of the signal passed therethrough, and these connections are as follows. The base is connected through resistor 60 to a lead 62 which, as will be seen, is established remotely either at a potential of [-03 v. or at 0 potential by a connection to ground. The base is also connected through resistor 64 to the anode of diode 66, the cathode of which is connected to lead 68. By a remote connection, lead 68 may be at either O or at -l v. potential. Each of the percussion keyers in the system is similarly connected to leads 62 and 68, these two leads, by a selection of the potentials set forth above, conditioning all of the keyers for short, medium, or long decay as required for the particular percussive effect.

As will be explained, when both leads 62 and 68 are grounded (zero potential), the decay is ata medium rate, and this rate is used in this specific example for harp, glockenspiel, and piano. When lead 68 is grounded and lead 62 is at -l-O.3 v., the decay rate is long and this rate is used for chime. When lead 62 is at +03 v. andV lead 68 is at -1 v., the decay is short, and this is used for Xylophone, Marimba, and Banjo.

The keyer is turned on, so as to cycle once, by a keying signal of about -{-2 7 v. supplied through lead 70. This lead is connected to ground through resistor 72 and through capacitor 74 to the cathode of diode 76 and the anode of diode 78. Diode 76 anode is grounded, and the cathode of diode 78 is connected to the transistor base through resistor 80, the base also being connected to ground through capacitor 82. Values used in this specific circuit are as follows, with resistors stated in ohms and capacitors in microfarads: Capacitor 52, 100; Capacitors 74 and 82, 33. Resistors 72, 1K; 64, 22K; 60, 47K; 56, 2.2K; 59, 680. Resistor 80 is variable depending upon the frequency, and is as follows: Frequencies 13 to 24, 120.0; 25 to 72, 820; 73 to 96, 390.

This specific keyer circuit is not a part of the present invention, and its operation is fully explainedin Milho Patent No. 3,247,306, to which reference is made for those desiring additional information. For the present purpose it is necessary to know merely that conduction through the transistor is initiated by a potential change on lead 70, and that the rate of recovery to cut off is determined as previously stated by the potentials established on the leads 62 and 68.

The filter drivers at 14 need not particular description since they are simply voltage amplifiers which provide the desired gain and may be entirely conventional. The

output lead 24 from the driver passes to the sine wave'A filter for the group indicated at 22 and to the piano and banjo format at 32.

The sine wave filter consists of a series connection through a resistor 90, capacitor 92, choke 94, choke 96, and resistor 98 to the output 26. There is also a connection between ground and the junction of chokes 94 and 96 by way of choke 100 and capacitor 102 in parallel. Choke 96 is bridged by capacitors 104 and 106 in series, and the common point between these capacitors is connected to ground through capacitor 108.

In this circuit, resistor 90 has a value of 2.2K; and 98, 15K. The chokes and capacitors vary with frequency and are as set forth in the following table, capacitors being indicated in microfarads and chokes in henrys.

Frequency Group 92 104 106 102 108 94 96 100 It will be recognized that this is a band pass lter suitable for the purpose and no particular novelty is claimed therein. Other designs could of course be substituted, so long as they provide an essentially clean sine wave at the output.

The percussion preamplifier at 28 needs no special description, since it may be conventional. Its output connection is indicated at 110, and it leads to the tab control system at 20 where it is connected as will be explained presently.

The bright wave signal to the piano and banjo formant passes through capacitor 112 and to the banjo preamplifier through resistor 114 and then-ce to the banjo lead 116 which extends to the tab switches 20. The piano connection leads from capacitor 112 through series resistors 118, 120, `and 122 to the piano preamplier 36, and by way of amplifier output lead 124 to the tab switches 20. In the formant, capacitor 126 is connected from ground to the junction ibetween resistors 118 and 120, and capacitor 128 is connected from ground to the junction between resistors 120 and 122. In this circuit, resistor 114 has a value of 100K, except for note 73 Where its value is 33K. Of the bright-wave-derived voices, 73 is the top note; it is handled separately from notes 67-72 only as a by-product of practical packaging considerations. Other resistors in ohms and capacitors in microfarads according to frequency groups are as follows:

The tab controlled system 20 comprises a plurality of gang switches actuated in groups by tabs labeled as follows: Chime, Xylophone, Harp, Marimba, Glockenspiel, Piano, and Banjo. All switches are shown in their off positionsthat is, With the particular stop silentand are turned on by pressing the appropriate tab. Leaving this group of switches to the left are a group of leads labeled in order from the bottom by the designations Fund., 1%, 2nd, 4th, 5th, 10th, and 3rd. These designations, in order, refer to the fact that an appropriate voltage on the particular lead will call for the fundamental, the one and one-fourth harmonic, the second harmonic, the fourth harmonic, the fth harmonic, the tenth harmonic, and/or the third harmonic of the particular key played. This is accomplished by a matrix of transistors, one row of which is shown near the upper left portion of the drawing.

The matrix or harmonic selector 18 consists of seven transistors, one for each harmonic (including the fundamental) it is desired to include in the synthesis, for each note within the compass of the percussion system. Some transistors may, of course, be omitted in the interest of cost-saving if less performance can be tolerated in a particular design. The row of seven transistors shown, therefore, is for the purpose of giving, as they are needed, the fundamental and the harmonics named above for the playing key for fundamental note number 13. An additional row will be used for each of the other playing keys for which synthesis type percussion is required.

These transistors preferably are of the silicon type, and types 2N3395 or 2N3565 are satisfactory for the purpose. They are indicated in order from the left by the numerals 130, 132, 134, 136, 138, 140, and 142. Each has its base connected to the center of a voltage divider made up of resistors 144 and 148, the former of which is connected to lead 146 While resistors 148 are connected individually to the various harmonic selecting leads as follows: 130 to the fundamental lead, 132 to the 1%, 134 to the 2nd, 136 to the 4th, 138 to the 5th, 140 to the 10th, and 142 to the 3rd leads. In the circuit shown, resistors 144 have a value of 10K and those at 148, 4.7K. The collectors are connected together and to a source of potential at +3 v., represented by the terminal 147. The lead 146 is connected such, as will appear, that the playing of keyboard key for note 13 will apply a potential of +11 v. thereto.

Each of the emitters is connected to the lead 70 for its particular percussion keyer. The transistor 130, for instance, which is for the fundamental for frequency 13, has its emitter connected to lead 70 for the keyer for signal 13, which, for this particular row of transistors, is of course the fundamental. Similarly, the emitter for transistor 132 is connected to the load 70 of the keyer Which is for the appropriate frequency to give the 1% harmonic to accompany fundamental 13, and so on.

The tab switched connections to the leads labeled Fund., 1%, 2nd, and so on, are such, as will appear, that when a particular harmonic is not desired, the lead will be at a potential of 5 v., whereas if the particular harmonic is needed, the lead will be grounded. If some of these leads are grounded and some are at a potential of -5 v., none of the transistors will be eiective until the appropriate key- No 1 in this instance-is played. When this occurs, a +11 v. potential will appear on lead 146 connected to all transistors in the row, and the potential at the transistor base will depend upon whether the lower end of the voltage divider, resistors 144-148 is at ground potential or at -5 v. If it is at ground, the potential at the base will be about 4.5 v., which saturates the transistor such that it acts as a switch. The 3 v. at the collector, with some attenuation, appears, therefore, at about +2.7 v. on the lead 70 and actuates its percussion keyer. If the lower end of the voltage divider is at -S v., the base will be at about zero volt, which is not enough to switch the transistor. Since the fundamental lead is connected to all of the transistors, one for each playing key, which control the various fundamentals, playing any key will activate the percussion keyer for its fundamental, providing the fundamental lead is grounded, and similarly with the various harmonics.

The keyboard and accessory system 16, which applies the +11 v. potential to the appropriate leads 146, is shown toward the left of FIG. 2. A bus bar is indicated at 150. It is connected through a normally closed switch 152 to switch contact 154 which can be moved to form a connection to a +11 v. supply 156. This is the usual switch condition, and places the bus at +11 v. Contacts 158, one for each of the leads 146, are arranged to engage the bus 150 whenever the appropriate key is played, thereby placing the proper lead 146 at +11 v. When reiteration is desired, the switch 154 can be shifted from the constant +11 v. source 156 to the output of a reiterator 160` which supplies an interrupted +11 v. at whatever rate is desired. This has the same elect as though the playing keys Were very rapidly pressed and released. The switch 154 may be connected to be actuated by a separate control tab, not shown. Also, the voltage reiteration system 160, which needs no special description, may have means to control the reiteration rate if desired.

An arpegg only tab 162, when pressed, opens the switch 152 and removes the +11 v. potential from the bus 150, so that playing the organ keys no longer actuates the percussion system through the circuits just described. The key will, of course, still play the organ sustained tones through systems which form no portion of this invention. Another set of playing key actuated contacts 170, however, cooperate with a second bus bar 172 which is maintained at +11 v. These contacts are interconnected at octave intervals as shown, so that contact for playing key 1 is connected to l3, 25, 37, 49, and 61, Whereas contact 2 is connected to 14, 26, 38, and 50, and so on. The twelve leads thus provided, represented by the two at 174 and 176, extend to an arpeggiator switch 178. A preferred form of arpeggiator is described in Young patent application Ser. No. 415,682. This device is essentially a miniature keyboard in which the individual keys are about an eighth of an inch wide, with all the keys the same length. It preferably extends over a several octave span as shown, and has a set of contacts 180 for each key. On the input side the contacts are connected together in octave groups, with the appropriate groups connected to the appropriate leads 174-176, and so on. Thus, holding any single note or chord, such as CEG for example, at the main keyboard 170-172 energizes all CEG contacts 180 at the arpeggiator switch 178. The output side of the switches 178, indicated at 182, are connected individually by leads, six of which are shown at 184, 186, 188, 190, 192, and 194, directly to the appropriate percussion key contacts 158. Therefore, whenever any arpeggiator key is touched, it will energize its lead 146, provided that the key for that note or any octavely related note is being held in the main keyboard. If no such key is held in the main keyboard, the corresponding arpeggiator keys will be dead.

Since the arpeggiator keys are small, the thumb or a finger can slide over the entire compass of this keyboard very easily and quickly. Thus, if any chord, CEG for example, is held at the main keyboard, running a iinger to they right over the arpeggiator keyboard will sound in succession the notes CEGCEGCEGCEG up the scale. Running the finger to the left, of course, sounds GECGECGEC and so down the scale. lf the arpeggio is the only percussive effect desired, the tab 162 is pressed to open switch 152. If arpeggio is desired along with percussive response from the main keyboard, then the tab 162 is placed in the up position to close switch 152 and energize bus 150.

Along the bottom of FIG. 2 is a row of percussion stop tabs which will serve as examples of what can be accomplished with this system. Others could be added or some subtracted, but a description of those shown will be suicient for the purpose. They are labeled from left to right: Chime, Xylophone, Harp, Marimba, Glockenspiel, Piano, and Banjo. Each of these provides a different combination of harmonics, either obtained by synthesizing sine waves or by formanting bright waves, and/ or a different percussive envelope. Each tab actuates a switch gang and the switches are shown in the positions they assume with the stops cancelled. Pressing a tab shifts all switches in a vertical line to their alternate positions. The switches are in two groups. Those in the lower group are of single-pole double-throw configuration, and control the harmonic content of the stop. Those in the uppery group are single-pole single-throw on-off switches, and control the stop envelope and serve other control functions.

Taking the bottom row of switches 200, there is one of these for each of the stops, Harp, Marimba, Glockenspiel, Piano, and Banjo. In the off position shown, their engaged contacts are connected in series from the Fundamental lead to a -5 v. lead 202 having a terminal at 204. Actuating any tab in this group breaks this series connection and grounds the lead labeled Fundamental. As explained previously, whenever` the Fundamental lead is at -5 v., the transistors 130 for the fundamentals cannot actuate their percussion keyers 12 even though a playing key is pressed. When the Fundamental lead is at ground, however, the keyers become conditioned for operation, and act whenever the appropriate key is played. Thus, operating the Harp, Marimba, Glockenspiel, Piano, or Banjo stop tab conditions the keyers for the fundamental, whereas actuation of the stop tabs Chime or Xylophone does not, since they have no switches 200;

In the next row there is only one similar switch, at 206, which alternatively connects the 1% harmonic lead to -5 v. or to ground. This switch is actuated by the Chime stop tab, and thus the 1% harmonic is keyed only when the Chime tab is pressed. The next row, connected to the 2nd harmonic lead, shows such series connected switches 208 for Chime and for Xylophone. The row for the 4th harmonic lead has such switches, at 210, for Chime, Marimba, and Glockenspiel, The 5th harmonic lead has a switch 212 for Xylophone only. The 10th harmonic lead has switch 214 for Glockenspiel only, and the 3rd harmonic lead has switch 216 for Chime only. The keyers lactivated for the various percussion stops is, therefore, as follows: Chime, 1%, 2nd, 4th, and 3rd; Xylophone, 2nd and 5th; Harp, Fundamental only; Marimba, Fund. and 4th; `Glockenspiel, Fund., 4th, and 10th; Piano and Banjo, Fundamental only.

Above the row of contacts 216 for the 3rd harmonic is la row of single-pole single-throw switches 220 shown in open position. These switches are connected in parallel between the -l v. percussion envelope control lead 68, previously mentioned, and ground. The lead 68 normally is xed at -l v. by the voltage connection at 222 and the voltage divider 224-226, but drops to ground potential whenever any of switches 220 is closed. These switches are arranged to be operated by the tabs for the stops Chime, Harp, Glockenspiel, and Piano. The next row of switches at 228 are similar and are connected between the +0.3 v. percussion envelope control lead 62 and ground. This lead 62 receives its +03 v. potential by way of voltage connection 230 -and voltage divider comprised of resistors 232 and 234. The switches 228, which when closed remove the +.3 v. potential from lead 62, are connected to be actuated by the tabs for Harp, Glockenspiel, and Pian-o. As previously explained, the Various combinations of these voltage connections to the keyers operate to give a long dec-ay envelope to the Chime stop, +.3 v. and ground; a medium decay to the Harp, Glockenspiel, 'and Piano, both leads grounded; and short decay for the Xylophone, Marimba, and Banjo, +.3 v. and -1 v.

Off to the right, in the Banjo line, there is a normally open yon-oif switch 240 between the lead 116 from the Banjo preamplier and the output terminal 30. When the Banjo tab is pressed, this switch closes and connects the banjo signal to the output system. Similarly, a normally open switch 242, actuated by the Pi-ano tab, connects the piano preamplifier output lead 124 to the output terminal 30 when the Piano tab is pressed. Note that since both of these stops use only activating leads to the Fundamental keyers, switches 200, only the fundamental bright waves will be keyed, formanted, and supplied to the output.

Along the top is a row of normally open switches 250 which are connected in parallel between the output terminal 30 and the lead 110 from the sine wave percussion preamplifier 28. There is one of these switches for each of the control tabs for every stop excepting Piano and Banjo in the present organization. Thus, pressing any of the stop tabs for Chime, Xylophone, Harp, Marimba, or Glockenspiel supplies the output with a mixture of sine FIGURE 2 depicts a representative and preferred complement of synthesized percussive voices. The harmonic makeup is conventional, with the exception of Glockenspiel which here is given an unusually effective treatment. Over most of the Glockenspiel tonal range the waves representative of the desired harmonics as called 5 strike tone is produced with appropriate choice of notes for by the switches 200, 206, 208, 210, 212, 214, and 216. 85 to 96. This is a frequency range from about 4185 Hz.

From the above discussion, it will be appreciated that to 7902 Hz. This octave is used over and over for the this system provides much more extensively than prior upper harmonic constituent for notes as low as E below organizations for the rather unusual and diverse requiremiddle C, as noted in the accompanying tabulation of ments for percussive instrument simulation. Percussive synthesis mixtures. This treatment of the upper harmonic instruments differ yin the length ofthe decay interval, constituent imparts to the Glockenspiel voice a strike tone and other than this, they fall into two general classes, of distinctive clarity. -The order of harmonic employed the requirements of which are antagonistic. Stringed inis as high as the 40th in the preferredembodiment. struments, whether struck, plucked, or strurnmed, re- The accompanying table illustrates a particularly efspond with a rather full, declining series of harmonics fective array of synthesized percussive voices. Above which is best obtained by the formanting or rather light manual key No. 17 (Dit), the topmost constituent for filtration of bright waves, 'which already have a full har- 4Glockenspiel lies in the octave 85 to 96; this high harmonic, declining series structure. In fact, sawtooth waves monic constituent preferably is considerably stronger are frequently referred to as string tones for this very 20 than the fundamental or other harmonics. In a preferred reason. The Harp may be considered as an exception to arrangement, fundamental and harmonics through the the above in that it its tone is almost a sine wave. 5th are of equal amplitudes, W-hile the Glockenspiel strike Some percussive instruments owe their characteristic to@ 1S made 10 .db Stronger The h 1ghf V01tage 0f the tonal quality to rather peculiar combinations of only a Strlke tone constituent can be obtained 1n varlous well few harmonics. This situation is a natural for the synknol/VH. Ways, WhlCh are IIO the sub1@ct 0f the Present thesis approach and, for all practical purposes, imposmventlonsible-at least in most instances-for the formant ap- While the emphasized strike tone constituent is essenproach. As an example, the Chime has no fundamental, tial to the improved Glockenspiel sound as herein debut has a 1% harmonic of the missing fundamental, plus scribed, suc-h a constituent is not desirable for other the 2nd, the 3rd, and the 4th. Another example: the 30 synthesized percussive voices, especially such as marimba Xylophone has the 2nd and 5th harmonics, but no fundaand Xylophone. Therefore in the preferred embodiment, mental, no 3rd, and no 4th. The Glockenspiel has the constituent tones only up through note No. 84 are used fundamental and 4th harmonic, plus a high frequency for percussive voices other than Glockenspiel. At the strike tone, the latter giving the instrument its peculiar lower end of the keyboard, one may end the strike tone ringing quality. `Such combinations as these are impractreatment Iwherever desired, including full coverage all tical of achievement by a formant approach, while a the iway to the bottom note. As a practical matter, the harmonic synthesis approach can simulate the desired efprototype sound does not extend that low in pitch; note fect to a striking degree. No. 17 is a convenient stopping point.

The completely consistent scheme described above for y'While we have described here a particular complement obtaining the same harmonic content for a particular syn- 40 of voices, it may be appreciated that the system described thesized stop, regardless of the key played, is of course frees the designer to make any choice of harmonics `which subject to variation, and such variation is advisable where appeals to him, since any transistor switch 130-142 can the higher harmonics called for 'would be above or close be connected to actuate any desired keyer lwithin the to the limit of audibility or musical effectiveness. entire frequency range of the percussion section of the instrument.

3rd 10th 5th 4th 2nd 1% Fund. Manual Key Harm Harm Harm. Harm. Harm Harm. Harm. KeyNo. Name 80 89 77 73 73 77 73 61 C 79 88 76 84 84 76 72 60 B 78 87 75 83 83 75 71 59 A# 77 86 74 82 82 74 70 58 A 76 85 73 81 81 73 69 57 G# 96 84 80 80 72 68 56 G 74 95 83 79 79 71 67 55 F# 73 94 82 78 78 70 66 54 F 72 93 81 77 77 69 65 53 E 83 92 80 76 76 68 64 52 D# 82 91 79 75 75 67 63 51 D 81 90 78 74 74 66 62 50 C# 89 77 73 73 65 61 49 C 79 88 76 84 72 64 60 48 B 78 87 75 83 71 63 59 47 A# 77 86 74 82 70 62 58 46 A 76 85 73 81 69 61 57 45 C# 75 96 84 80 68 60 56 44 G 74 95 83 79 67 59 55 43 F# 73 94 82 78 66 58 54 42 F 72 93 81 77 65 57 53 41 E 71 92 80 76 64 56 52 40 D# 70 91 79 75 63 55 51 39 D 69 90 78 74 62 54 50 38 C# 68 89 77 73 61 53 49 37 C 67 88 76 72 60 52 48 36 B 66 87 75 71 59 51 47 35 A# 65 86 74 70 58 50 46 34 A 64 85 73 69 57 49 45 33 G# 63 96 72 68 56 48 44 32 G 62 95 71 67 55 47 43 31 F# 61 94 70 66 54 46 42 30 F 60 93 69 65 53 45 41 29 E 59 92 68 64 52 44 40 28 D# 58 91 67 63 51 43 39 27 D 57 90 66 62 50 42 38 26 C# 56 89 65 61 49 41 37 25 C 55 88 64 60 48 40 36 24 B 54 87 63 59 47 39 35 23 A# 53 86 62 58 46 38 34 22 A 3rd 10th 5th 4th 2nd 1% Fund. Manual Key Harm. Harm Harm, Harm. Harm. Harm. Harm, KeyNo. Name 52 85 61 57 45 37 33 21 G# 51 96 60 56 44 36 32 20 G 50 95 59 65 43 35 31 19 F# 49 94 58 54 42 34 30 18 F 48 93 57 53 41 33 29 17 E 47 68 56 52 40 32 28 16 D# 46 67 55 51 39 31 27 15 D 45 66 54 50 38 30 26 14 C# 44 65 53 49 37 29 25 13 C 43 54 52 48 36 28 24 12 B 42 63 51 47 35 27 23 11 A# 41 62 55 46 34 26 22 10 A 40 61 49 45 33 25 21 9 G# 39 60 48 44 32 24 20 8 G 38 59 47 43 31 23 19 7 F# 37 58 46 42 30 22 18 6 F 36 57 45 41 29 21 17 5 E 35 56 44 40 28 20 16 4 D 34 55 43 39 27 19 15 3 D 33 54 42 38 26 18 14 2 C# 32 53 41 37 25 17 13 1 O From the above description of the invention as embodied in a specific structure, it will be apparent that modifications can be made without departing from the scope or spirit of the invention, and that therefore the scope of the invention is to be measured from the scope of the following claims.

In the claims, the word harmonic is used in its generic sense and includes the rst harmonic or fundamental as well as harmonics which are partials of the fundamental.

Having described our invention, what We claim as new and useful and desire to secure by 'Letters Patent of the United States is:

1. In an organ percussion system, a system of playing key actuated contacts, a source of complex wave tone signals representative of notes of the musical scale, a percussive keyer for each of said tone signals, circuit means collecting the outputs of said keyers in adjacent semitone groups, means for filtering each of said groups to obtain the substantially uncontaminated fundamentals of said tone signals, means for connecting the outputs of said tilters to an output system, a switching matrix having a multiplicity of switching elements each adapted to connect an individual tone signal to the output when activated, said switching elements adapted to 4be activated when a pair of leads connected thereto are activated jointly, a harmonic selector having means for activating one set of said pair of leads, said playing key operated switches adapted to activate the other set of said pair of leads, the playing key leads for each playing key extending to each matrix element to be controlled by the particular key, the harmonic selector having a plurality of positions each controlling a different combination of selected harmonics and activating sets of leads for the harmonics selected, the last said sets extending to the matrix switching elements controlling the selected harmonics, and circuit means connected from said matrix to said keyers for actuating the appropriate keyer whenever a matrix switching element calls for a tone signal controlled by the particular keyer.

2. The organ percussion system as called for in claim 1 in which the source of complex wave signals provides bright wave signals having a full harmonic series.

3. The organ percussion system as called for in claim 2, including formanting means adapted for selected connection to the group outputs of said percussion keyers for formanting the grouped bright wave signals from said keyers and for connecting the outputs of said formanting means to the output system means.

4. The organ percussion system as called for in claim 3, including means actuated coincidentally with said formanting means for activating said harmonic selector lead for the fundamental keyers only.

5. The organ percussion system as called for in claim 1 in which there is a group of adjacent semitone tone signals from said source which have a higher voltage level than others of said tone signals.

6. The organ percussion system as called for in claim 5 in which the group of higher voltage tone signals comprises atleast the highest frequency octave available from said source.

7. In an organ percussion system, a system of playing key actuated contacts, a source of tone signals representative of notes of the musical scale, a percussive keyer for each of said tone signals, circuit means collecting the outputs of said keyers, means for connecting the outputs of said keyers to an output system, a switching matrix having a multiplicity of switching elements each adapted to connect an individual tone signal to the output when activated, said switching elements adapted to be activated when a pair of leads connected thereto are activated jointly, a harmonic selector having means for activating one set of said pair of leads, said playing key operated switches adapted to activate the other set of said pair of leads, the playing key leads for each playing key extending to each matrix element to be controlled by the particular key, the harmonic selector having a plurality of positions each controlling a different combination of selected harmonics and activating sets of leads for the harmonics selected, the last said sets extending to the matrix switching elements controlling the selected harmonics, and circuit means connectedfrom said matrix to said keyers for actuating the appropriate keyer whenever a matrix switching element calls for al tone signal controlled by the particular keyer.

8. The organ percussion system as called for in claim 7 in which there is a group of adjacent semitone tone signals from said source which have a higher voltage level than others of said tone signals.

9. The organ percussion system as called for in claim 8 in which the group of higher voltage tone signals comprises at least the highest frequency octave available from said source.

10. The organ percussion system as called for in claim 1 in which a second keyboard is provided and in which one keyboard selects the note within an octave to be sounded and the second keyboard selects the octave in which said note is to be sounded, and in which coincident action of the playing keys in both keyboards is required to sound a note.

11. The organ percussion system as called for in claim 7 in which a second keyboard is provided and in which one keyboard selects the note within an octave to be References Cited sounded and the second keyboard selects the octave in which said note is to be sounded, and in which coincident UNITED STATES PATENTS action of the playing keys in both keyboards is required 2,841,043 7/1958 Schfelbe 84-1-13 to sound a note. 5 2,953,958 9/1960 G eorge 8f4-1.11 X

12. The system as called for in claim 7 wherein twelve 219 86,964 6/1961 Blssonette et al 534-126 or fewer high-order harmonic constituent tones are used 3,207,835 9/1965 Holman et al 84-1-26 X consecutively and repeatedly over a several octave fundadental tonal range HERMAN KARL SAALBACH, Prlmary Examiner 13. The system as called for in claim 8 wherein twelve 10 SAXFIELD CHATMON, IR., ASSStanf Examiner or fewer high-order harmonic constituent tones are used consecutively and repeatedly over a several octave funda- U'S' C1- X-R' mental tonal range. S11- 1.03, 1.11, 1.26

PO-050 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,480,718 Dated Nollgmher 25 :|969

Inventor(s)N0rmaI1 R- KOhlS, Clarence A. lykl, Jr ,6: William R,

A res It is certified that error appears in the above-identified ptent' and that said Letters Patent are hereby corrected as show-n below:

Col. 3, line 62, "cab" should be -tab Col. 4,

line 72, "format" should be "formant" Col. 6, line 38, "load" should lead In the table at the top of column ll, in the column labeled "10th Harmonic", the numeral between "65" ard "63" should be --6, not "54". In the same table, in the column labeled "Key Name", "D'l in the fourth line up from the bottom should be D# SIGNED AND SEALED Aue 25197!) (SEAL) n@ new Munmxr. mm1 E. m.

L M-testing om Oomussionar o! Patents 

